Aeronautical propeller



May 12,, 11931, 5 REED L8Q4A=33 AERONAUTICAL PROPELLER Filed Dec. 5. 1928 ATTORN lllgllllll iilik.

Patented May 12, i 1931 UNITED STATES PATENT OFFICE SYLV'ANUS ALBERT REED, OF NEW YORK, N. Y., ASSIGNOR TO THE REED PROPELLER CO. INC., OF NEW YORK, N, Y., A CORPORATION OF NEW YORK AERONA'UTICAL PROZPELLER I Application filed December 3, 1928. Serial No. 323,480.

My invention relates in general to metal aeronautical propellers and has reference more particularly to the type of metal propeller blades disclosed in U. S. Patents Nos. 1,463,556 and 1,518,410, granted to me July 31., 1923, and December 9, 1924, respectively,

and. in which the blades are preferably solid and of forged strong light weight metal alloy and thinrelatively to their thrust loads.

In making propellers of this type of large diameters, such as may be used on motors geared down to a slower propeller rotation, there are manufacturing difficulties and excessive weight and much expense is involved. I have now devised a novel form of this type of propeller which can be made from rolled solid metal plates of much less thickness than the maximum blade thickness, and which plates are staple articles of commerce of moderate cost, and furthermore. such plates are easily, cheaply and safely cut and bent to make up different propeller designs of a large range of sizes and shapes.

Using the expression inner portion to mean that portion of the blade between the propeller drive shaft and about midway to the tip, and the expression outer portion to mean the remainder of the blade to its tip. I prefer to make substantially all of the ner portion composite, but substantially all f ihe outer portion integral and solid, and l: thus obtain the thickness or camber neces ary for torsional rigidity against change pitch.

also prefer to compress or form eac element in the axial region into a bulged troug 'i-like form with convexity outward. Ya order to permit the use of a hub whose axial length is less than the original width the element, and this compressed or i L ed portion of the element will then also e provided with a lateral offset distortion, Mapted to form when assembled with the alter element, an orifice in which a hub may r be attached.

I am aware that has been proposed to make propellers of duplicate sheets of metal combined to form blades entirely hollow,

* and therefore composite, but blade tips of such construction cannot be made to give high efficiency, whereas the blades in my present invention have a substantial part of their outer ends integral and solid, and therefore capable of being formed for high eiiiciency, so that this feature is an important improvement.

Other important advantages possessed by my improved propeller structure will appear from the detailed description hereinafter given.

I have illustrated a type of my improved propeller construction in the accompanying drawings, wherein;

Figure 1, shows a plan view of a metal blank from which is made one of the two elements forming my improved propeller.

Figure 2, shows a plan view of theelement after it has been formed and distorted into its final form for assembling with the other duplicate element.

Figure 3, shows a view in elevation of vthe completed propeller made from the two assembled elements, the view being taken looking in the line of the axis of rotation and through the center of the hub.

Figure 4c, shows a side elevation of the propeller shown in Fig. 3.

Figure 5, is an enlarged view of a crosssection of the blade at its composite or overlap portion, showing one element arched or bent to a camber.

Figure 6, is an enlarged view of a crosssection of the outer integral and non-composite portion of the blade. 4

Figure 7, is an enlarged view of a crosssection of the propeller, the plane of the section passing through the hub center.

Figure 8, is an enlarged view of a crosssection of the propeller taken on a lane transverse to the hub and at right-ang es to that in Fig. 7.

Figure 9, is an enlarged view of a crosssection of the propeller at the blade root and on a plane parallel with the hub axis.

Referring to the drawings, which are somewhat diagrammatic in character, the

. known suitable manner, will thus about 15 feet long and about 14 inches wide,

which is sawed or cut at one end i, to the proper blade outline including the tip,'and at the other end 2, to dimensions suitable for an overlap of about 6 feet on the other oppositely arranged element, and conformable in outline thereto, with allowance for camber; the said other element being indicated with the reference numerals 1 and 2 in its correspondingly shaped parts.

Each element is then twisted continuously in the same direction from end to end comformably to the desired pitch angles, resulting in the form shown in Fig. 2, the

axial region being then shaped by dies or otherwise into an outwardly bulging troughlike'form, as at 3, with an offset to pass around a hub member. This peculiar axial region formation of the cooperating element 1, 2*, is indicated at 3 on said duplicate. The two elements are then assembled as a unit, as shown more particularly in Figs. 3 and 4, and the overlap of one is secured to the overlapped part of the other by a suitable number of rivets 4, or otherwise. The overlapping parts of each blade being united or attached together securely 'in at? well orm a unit structure.

The propeller thus composed of the two elements has correct pitch angles on each blade from root to tip, and each blade is composite for a large fraction, in this case all, of the inner portion of the blade, as shown particularly in Fig. 5, and if desired for a part of the outer portion of the blade also, but most of the remainder of the outer portion of the blade is integral and solid, as shown in cross-section in Fig. 6. The contact edges of the overlap and overla ped parts are then feather edged or otherwise adapted for a'desired fit and contour and the blades are then cut to form plan and bent arched or cut to suitable camber. I

The ofi'sets 3 and 3, of the respective elements, being disposed opposite to each other have a trussing effect and also provide an interspace of considerable size for receiving a hub. The overlapping parts gradually come into contact with each other and this contact is intimate at the extremity of each overlap, as indicated in Fig. 5.

I prefer the hub arrangement which I have herein shown in Figs. 3, 7, 8 and 9, consist-ing of a steehsleeve .5, adapted by keyway 6, or splines or otherwise, for mounting on an engine-shaft overhang, and having a central flange 7,. substantially parallel to the plane of rotation, and of substantially rectangular elongated plan, with projections 8, at each corner, which projections pass through slots 9, cut through the elements. The parts of the projections 8, which are outside of the elements, are provided with holes or eyes 10, through which pass bands 11, encircling the. propeller and having means 12, for drawing up in order to bind firmly the blade roots to the hub. The long side edges of the hub-flange 7, fit against the inner surfaces of the offsets and serve to reinforce and strengthen the structure and give stability to it.

I may provide chucks or fillers of wood 13, or other suitable light weight mate-rich to brace and support'the hollow spaces or to sustain the compression forces of the clamps, bolts, rivets or other binding means.

The bulgingand constriction of the two elements at the binder '11, when assembled therewith, result in giving the blade an abutment, supporting and resisting the radial tension caused by centrifugal force, in consequence of which the bolts, rivets or other means of securing the overlapped parts together, need have a small share only in carrying these stresses, 0!, if slotted as hereinafter described, then no share at all.

The resulting propeller has several advantages. \Vithout having an excessive weight, it can still provide at the inner portions of the blades a suflieient camber to afford adequate stability of pitch. The central abutment supports most of the centrifugal stresses, and the overlap of each element will balance a very large part of the centrifugal stress and thereby relieve the abutment materially.

The thickness of the elements at all radii is quite adequate to afford a cross-section giving a large margin of safety against centrifugal and bending stresses. The main advantage, however, of my improved form of construction is that I obtain a blade which, while composite in the more slowly moving portions, nevertheless is integral and solid in the more rapidly moving portions, and I thus obtain most of the advantages incident to the solid thin blade type of propeller described in my patents hereinabove mentioned.

The central construction afiords great rigidity and makes it possible to use a steel hub of great simpilicity and lightness.

I prefer to extend the bolt-holes for the attaching means 4, by slotting those in portions 1 and 1 of the res ective elements, in a direction away from t e tip of its element, as shown in Fig. 4, and thus relieve mainly or entirely the attaching means 4, from the stress of,centrifugal force, in case the elements should stretch under such stress, and the latter will then be borne mainly or newness parts 11, which blades are hollow in the immediate vicinity v of the hub, are composite for a substantial part of the blade length, and are integral and solid from thence to the tips.

2. A metal aeronautical propeller, each blade of which is hollow at the root, is composite though solid from the root outwardly for a substantial portion of its length, and

which, in the vicinity of the blade tip, is

- of a hub orifice, a metal hub inserted in said integral and solid.'

3. A metal aeronautical propeller, each blade of which at its inner end, continues integrally beyond the propeller hub and overlaps the opposite blade throughout a substantial ortion, but less than two thirds of the len t of said opposite blade, and which,

throug out the remaining portion of its length is integral and solid.

4. A metal aeronautical propeller, each blade of which at its inner end continues integrally beyond the propeller hub and overlaps and is secured to and reinforces a substantial part of the length of the opposite blade at least one half though less than two-thirds of the entire length thereof, and which, throughout the remaining ortion of its length is of a one piece integral and solid construction.

5. A metal aeronautical propeller of two integral blade elements, each of which continues integrally past the propeller hub and overlaps and is joined to a substantial part of the length of the opposite blade, less thanthe' entire length thereof, and the blade elements ofiset in the central region, so as to pass respectively on opposite sides of a hub orifice, and with a reinforced constriction in each element beyond the hub providing a an abutment bearing against the propeller hub and sustaining the centrifugal stresses.

6. A.metal aeronautical ropeller of two integral blade elements, eac of which continues integrally past the propeller hub and overlaps and is joined to a substantial part of the length of the opposite blade, and the blade elements having ofi'sets in the central region to pass respectively on opposite sides of a hub orifice, a metal hub inserted in said orifice and having a flange substantially in the plane of rotation of the propeller and flange projections passing through and engaging side orifices in said blade elements, and binding means associated with said projections outside of the blade elements and securing the propeller to the said hub.

7. A metal aeronautical propeller of two integral blade elements, each of which continues integrally past the propeller hub and overlaps and is joined to a substantial part of the length of the opposite blade, but does not extend to the integral opposite blade tip, and the blade elements having ofisets in the central region to pass respectively on opposite sides of a hub orifice, a constriction at the root of each blade bearing against the hub, and clamping means encircling said constricted parts.

8. A metal aeronautical propeller of two integral blade elements, each of which continues integrally past the propeller hub and overlaps and is oined to a substantial part I of the length of the o posite blade, said blade elements having 0 sets in the central region to pass respectively on opposite sides orifice and having a flange substantially parallel to the plane of rotation of the pro eller and flange projections passing throug and engaging side orifices in the said blade elements, a constriction at the root of each blade bearing against the hub, and clamping means encircling said constricted vparts and attached to said flange projections for securing the propeller to said hub.

9. A metal aeronautical propeller, whose blades are composite for not less than the inner third of the blade lengths, and are integral solid, and of one piece construction throughout the outer third of their lengths.

10. A metal aeronautical propeller, whose blades are composite for substantially the inner half of the blade lengths, and are integral and solid from thence to the tips, hollow spaces being formed between the composite elements'and light-weight bracing means, being disposed within said hollow portions for reinforcing said blades, said racing means only filling a part of the hollow portions.

11. A metal aeronautical ropeller comprising a hub, blades exten ing outwardly from the hub, each of the said blades being provided with a hollow portion adjacent to the hub and each having a solid portion of substantial length in the vicinity of the tip of the blade. 1

12. A metal aeronautical propeller, comprising a hub and blades extending outwardly from the hub, each of the said blades having a composite hollow section adjacent to the hub and each having an integral and solid portion of substantial length in the region of its tip.

Signed at New York City, in the county of New York and State of New York this 30th day of November, A. D. 1928.

SYLVANUS ALBERT REED. 

